RENOPROTECTIVE EFFECTS OF IMEGLIMIN IN A MODEL OF ACUTE KIDNEY INJURY

Acute kidney injury is estimated to affect more than 13 million people worldwide, yet effective therapies remain limited. Imeglimin is a recently approved antidiabetic agent that enhances glucose-induced insulin secretion and improves insulin resistance. In addition to hypoglycemic effects, imeglimin has been shown to exert protective effects on mitochondria and to reduce production of reactive oxygen species (ROS). Since mitochondrial damage and ROS production are the hallmarks of acute kidney injury, we analyzed the effects of imeglimin on acute kidney injury using an ischemia reperfusion injury (IRI) model.

In male C57BL/6J mice, IRI was induced by clamping the right kidney pedicle for 23 minutes, followed by removal of the left kidney. Imeglimin or the vehicle, methylcellulose, was administered orally twice a day, starting 12 hours before IRI and continuing until sacrifice. Mice were sacrificed 24 hours after IRI. At the time of sacrifice, blood was collected for the measurement of serum creatinine (Scr) and blood urea nitrogen (BUN). Kidney tissues were snap-frozen and were used for histological analysis and RNA extraction. RNA sequencing and quantitative real-time PCR were performed. HK2 human proximal tubule cells were incubated under hypoxic conditions for 24 hours, followed by reoxygenation under normoxic conditions for 4 hours prior to ROS analysis using DCFH-DA.

Levels of Scr and BUN were significantly elevated in the IRI group relative to the sham group. These increases were markedly attenuated in the IRI + imeglimin group. Histological analysis revealed that kidney injury—induced by IRI, primarily in the proximal tubules—was significantly attenuated by imeglimin. In the kidneys from the IRI + imeglimin group, 845 genes were downregulated and 349 genes were upregulated compared to the IRI group, respectively. Gene ontology analysis revealed enrichment of biological processes including positive regulation of tumor necrosis factor production, base-excision repair, and positive regulation of inflammatory response in the downregulated genes, whereas processes including lipid metabolic process and regulation of sodium ion transport were enriched in the upregulated genes. Together with qPCR results for genes including megalin and inflammatory markers, these results suggest that imeglimin inhibits inflammatory pathways, while contributing to the preservation of normal kidney function. Since base-excision repair pathway was among the enriched pathways in genes downregulated by imeglimin, we assessed DNA damage by staining kidney tissues with γH2AX. The IRI-induced increase in the number of γH2AX-positive nuclei in proximal tubules was significantly suppressed by imeglimin. Finally, the effects of imeglimin on ROS production was investigated using HK-2 cells. Increase in ROS induced by transient hypoxia was significantly attenuated by imeglimin.

The present study revealed that imeglimin exerts renoprotective effects in an experimental model of IRI. Imeglimin attenuated the inflammatory response, including DNA damage, and supported the maintenance of gene expression relevant to renal function. A reduction of ROS production may contribute to its renoprotective effects.